(1) Field of the Invention
The present invention relates to an actuator controller and a method for controlling such an actuator controller.
(2) Related Art Statement
Actuators, which are instructed as to its activation position to perform movement or rotation, are generally each equipped with a location sensor, such as an encoder or a potentiometer, that indicates the position of the actuator itself. Many actuator controllers each control the actuator such that the position indicated by the location sensor may be in conformity with a target one. See JP-A 2005-073377.
(3) Problems to be Solved by the Invention
The above actuator controller commonly makes a control, while positional signals of given bit counts are assigned over an driven range of the actuator.
Consider a case in which positional signals of 256 bit counts are assigned to the actuator having a rotational range of 256°, for example. In this case, an angle of 1° is assigned to one bit with respect to bit No. 1 to bit No. 256 over the rotational angle of 256°. The controller outputs a bit of a necessary number of rotations to the actuator, the actuator outputs a positional signal at the rotation position to the controller, and the controller controls the actuator so that these signals may be in conformity with each other. For example, if rotation is to be effected at an angle of 180°, the controller outputs bit No. 180 to the actuator so as to drive the actuator such that the positional signal of the actuator may be 180°.
In an air blower for an automobile, such an actuator is used to drive an open air introducing door which turns over air suction ports. In the state that the rotation angle of the actuator is “zero”, an internal air-circulating operation is performed in which a car interior air is circulated, while the open air introducing door is closed to introduce no air from the outside of the car into the car interior. In the state that the rotation angle of the actuator is the largest, open air introducing operation is performed, in which open air outside the car is introduced into the car interior, while the open air introducing door is fully opened. Now, this case will be considered. In such an air blower, if the location sensor is out of order in the state that the rotation angle of the actuator is “zero” and the actuator is not moved even when the controller outputs a target position to the actuator, the actuator is not driven in the state that the open air introducing door is closed. Consequently, only the internal circulating operation is performed. In this case, a car glass may unfavorably become cloudy, if there is a large temperature difference between inside and outside of the car. This may cause poor visibility.